Philip Hazel is a computer programmer best known for writing the Exim mail transport agent in 1995 and the PCRE regular expression library in 1997. He was employed by the University of Cambridge Computing Service until he retired at the end of September 2007. In 2009 Hazel wrote an autobiographical memoir about his computing career.
Hazel is also known for his typesetting software, in particular "Philip's Music Writer", as well as programs to turn a simple markup into a subset of DocBook XML for use in the Exim manual, and to produce PostScript from this XML.
- Exim: the Mail Transfer Agent (O'Reilly Media, 2001)
- The Exim SMTP Mail Server, (UIT Cambridge, 2003, 2nd edition 2007)
- From Punched Cards To Flat Screens, 2009
- Evi Nemeth; Garth Snyder; Trent R. Hein (2007). Linux administration handbook. Addison-Wesley. p. 621. Retrieved 23 December 2010.
- Gerald Carter (2003). LDAP system administration. O'Reilly Media, Inc. p. 165. Retrieved 23 December 2010.
- Jeffrey E. F. Friedl (2006). Mastering regular expressions. O'Reilly Media, Inc. p. 440. Retrieved 23 December 2010.
- "From Punched Cards To Flat Screens - A Technical Autobiography By Philip Hazel" (PDF).
- Philip's Music Writer.
- Peter Le Huray (1990). Authenticity in performance: eighteenth-century case studies. Cambridge University Press Archive. p. 17. Retrieved 23 December 2010.
-  Philip Hazel's personal website